This application is related to and claims the benefit of priority from Norwegian Patent Application No. 2002 2130, filed on May 3, 2002, the entirety of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a frame for coiling the surplus length of an overhead cable when two cable sections are spliced in a splicing box. Such cables are usually suspended from wooden/concrete poles or from steel towers. The invention is particularly adapted to be used with Optical Fiber Composite Ground Wires (OPGW). This is a rather rigid product.
2. Description of Prior Art
As is known, an optical fiber is capable of transmitting a large amount of information with a very low transmission loss and is a good insulator with no electromagnetic induction. It has therefore been proposed to provide the ground wire used in connection with overhead power transmission lines with an optical fiber cable in the center to form an economical information loop or network.
There is sometimes a need to splice two OPGW cables. Such splicing is required when two cable sections have to connected at a pole or tower.
An operator who will put the spliced connection in a splicing box makes this operation on the ground. To do this, the operator needs to have an overlength or surplus of cable. After the splicing operation, excess lengths that are no longer required have to be stored several meters above the ground level.
The only known solution consists in using a static X-shaped frame around which the cable is coiled so as to be latched into four slits that turns outwards, a latch pin being placed on the top of each slit to prevent the cable to coil out. This X-shaped frame is fixed at a desired height to a wooden pole or a steel tower. This solution induces some difficult problems because of the manpower required to coil the cable and in order to force it into the slits of the frame mounted on the wooden pole or the steel tower.
An object of the invention is to provide a frame for coiling the surplus length of a spliced overhead cable allowing to coil the cable easily without excessive manpower.
More precisely, the invention provides a frame for coiling a surplus splice length of an overhead cable installed on poles or towers characterized in that said frame comprises a coiling chamber for the coiling of said surplus splice length, said coiling chamber comprising:
an interior in which said surplus splice length is coiled,
an outer edge allowing the free rotation of said frame about a shaft,
said surplus splice length being pushed from underneath by an operator and being further pushed and held by its own restoring force against said outer edge of said coiling chamber, said pushing and holding effects inducing said rotation of said frame.
Thus, using this frame, the coiling becomes very easy. When the operator starts indeed to push the cables from underneath, the restoring force of the surplus splice length will push and hold the cable in the outer edge of the coiling chamber and make it possible to start the rotation of the frame. This restoring force is a self-going force of the surplus splice length that shoves said surplus splice length inside said coiling chamber.
Advantageously, said frame comprises an axle in the center of said chamber. The axle can be a hollow axle to be fitted into the shaft in order to allow the rotation of said frame around said shaft.
Furthermore, said axle includes means for locking the coiling frame in order to prevent a rotation of said frame and to prevent said frame from falling down.
Advantageously, the frame has a circular shape.
In a preferred embodiment, said frame comprises at least four stems extending from the center of said frame, each one of said stems having a U-shaped folded up end delimiting said interior of said coiling chamber.
Advantageously, said frame comprises six stems and said coiling chamber has a circular shape, each stem being on the opposite side of another stem along a diameter of said coiling chamber.
Advantageously, the opening of U of said U-shape is turned towards the center of said frame.
In a preferred embodiment, said U-shaped end is connected to a ring centered in the center of said chamber.
Advantageously, the frame comprises a fastening plate in order to fasten a splicing box to said frame.
Furthermore, said fastening plate can comprise means for adjusting the position of said splicing box.
Another object of the present invention is to provide a system for splicing overhead cable comprising a frame according to the invention, said system including means for attaching said frame to a predetermined height of a pole or a tower.
In a preferred embodiment, said frame comprises a hollow axle in the center of said chamber, said means for attaching including a shaft, said hollow axle being rotatable around said shaft.
In one embodiment, said means for attaching is a curved base plate such that said frame can be attached to a cylindrical pole like a wooden pole.
In another embodiment, said means for attaching is a plane base plate such that said frame can be attached to a steel tower.
Advantageously, the system comprises a fastening plate in order to fasten a splicing box to said frame and a splicing box fastened to said fastening plate.
The system may comprise means for including a branch-off overhead or underground cable in the frame and in the splicing box.
Another object of the present invention is to provide a method for coiling a surplus splice length of an overhead cable installed on a pole or a tower using a system according to the invention and having the following steps:
threading the cable ends to be splice inside said chamber on the ground,
splicing said cable ends and installing the splice in said splicing box on the ground, two portions of cable representing said surplus splice length,
fastening said splicing box to said fastening plate of said frame,
lifting said frame with said splicing box at said predetermined height of said pole or said tower,
snapping said frame onto said shaft,
pushing said surplus splice length from underneath, said surplus splice length being further pushed and held by its own restoring force against said outer edge of said coiling chamber, said pushing and holding effects inducing said rotation of said frame.